Data mining and decision support technologies use machine learning to support data classification and to implement decision trees. Technology areas that utilize machine learning include merchandise mark-down services in retail applications, clinician diagnosis and treatment plan assistance based on similar patients' characteristics and general purpose data mining. Decision or classification trees have become one of the most popular data analysis and decision making support tools in recent years due to the ease of understanding of their operation. Numerous algorithms and software packages are available to construct and visualize decision trees.